Date: Mon, 6 Dec 1999 09:58:59 -0800 (PST) From: Matthew Jacob <mjacob@feral.com> To: Mike Smith <msmith@freebsd.org> Cc: hackers@freebsd.org Subject: Re: tty level buffer overflows Message-ID: <Pine.BSF.4.05.9912060956510.3258-100000@semuta.feral.com> In-Reply-To: <199912060441.UAA00805@mass.cdrom.com>
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> > > > > Er, you should read the sio(4) manpage too. tty-level buffer overflows > > > have nothing to do with interrupt latency/execution time. > > > > You mean this: > > > > sio%d: tty-level buffer overflow. Problem in the application. Input has > > arrived faster than the given module could process it and some has been > > lost. > > Yup. Ignore the "problem in the application" part, as that predicates > that the kernel and driver are working properly, which doesn't seem to be > the case. The problem here is that the buffer between the top side of > the driver and the application isn't being drained fast enough. It would > be educational to know what the app is sleeping on when these messages > are emitted; just dropping to ddb and using 'ps' would probably be > enough. There has to be some reason that the process is either not being > woken when data arrives, or is being held up somewhere else for long > enough that the clist overflows. That's tough because it's transitory and hard to notice as I only rlogin into this machine! Sounds to me a gdb breakpoint is what's needed, but this is difficult to do for this machine. > Does the problem still manifest with the recent scheduler changes? > Perhaps the comms processes are being unfairly scheduled against for some > reason? The kernel is a November 12 kernel. Maybe it's better now. However, I'm still staggering under the recent bdev changes - when everything has settled down and all my other freebsd machines can boot all the way up and are all up to date, I'll revisit this. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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